Field of the Invention
The present invention relates to a key switch structure.
Description of the Related Art
FIG. 5 is a view showing a conventional key switch structure.
In the key switch structure, a control panel comprising a key top 2 with a pressing protuberance 3, a key sheet 5 supported on a key sheet reinforcement plate 7, and a key switch 6 mounted on a key base 8 is disposed in a case body 1. If the center position of the key top 2 is not aligned with the center position of a keyhole 11 in the case body 1 of the key switch structure of this type, as shown in FIG. 5, a gap between the key top 2 and the inner wall surface of the keyhole 11 is not uniform throughout the circumference of the key top 2, so that the external appearance is poor. Further, a problem easily occurs that the key top 2 is caught by the edge of the keyhole 11 in the case body 1 when its corner is pressed.
Thus, it is advisable that the key top 2 be located near the center position of the keyhole 11 in the case body 1 so that the gap between the key top 2 and the inner wall surface of the keyhole 11 is uniform throughout the circumference of the key top 2.
Japanese Patent Applications Laid-Open Nos. 2004-071429, 8-292829 and 2002-075130 disclose techniques in which a positioning mechanism is provided to a key switch structure such that a key switch is positioned in the center position of a keyhole by the positioning mechanism.
In the positioning techniques as described in the above patent documents, however, a special mechanism is needed to align the center position of the key top with the center position of the keyhole, so that there are problems of increased manufacturing costs and time-consuming assembly.